Victorian, but not the Victorian era as we know it. For example, page 11 describes how Florence Nightingale led the Charge of the Light Brigade to capture the Russian space elevator at Balaclava.

The solar-steam-electric-etheric space drive is pretty cool, but my favourite bit of technology would have to be their computer jargon organised around "beekeeping" - no insects are involved, just a highly original take on the familiar idea of difference engines.